happy girlThis only kid is A-OK.Photo: Omar GurnahSnooki of MTV’s Jersey Shore is immature, whiny, and self-involved — in other words, your typical reality-show star. But a New York Times article about her improbable rise to fame pinpoints one of her less typical qualities: “Not surprisingly, Snooki is an only child,” writes Cathy Horyn.

Ouch. Harshing on the only kids. Surely many other immature, whiny, and self-involved reality-show participants have siblings, but nobody’s pointing that out.

This is just the sort of groundless prejudice that Bill McKibben set out to counter when he wrote the book Maybe One: A Case for Smaller Families in 1998. McKibben and his wife decided to have just one child, inspired in part by their concern for the environment. But they wanted to know if their daughter would suffer from a lack of siblings, so McKibben delved into the research and found the answer: a resounding “no.”

I called up McKibben recently to chat about how Maybe One is just as relevant today as it was a dozen years ago. “The most common reason that people give for having a second child is so that their first child won’t be an only child,” McKibben told me. “There can be good reasons to have more than one kid, but that is not one of them. The most novel and interesting part of Maybe One was showing that only children are fine, indistinguishable, completely normal, not subject to the problems that people always diagnose, like being spoiled.”

Lauren Sandler, reporting for Time last year, talked to experts and found the same thing:

Twenty-five years ago, [University of Texas at Austin professor Toni Falbo] and colleague Denise Polit conducted a meta-analysis of 115 studies of only children from 1925 onward that considered developmental outcomes of adjustment, character, sociability, achievement and intelligence. … Generally, those studies showed that singletons aren’t measurably different from other kids — except that they, along with firstborns and people who have only one sibling, score higher in measures of intelligence and achievement. No one, Falbo says, has published research that can demonstrate any truth behind the stereotype of the only child as lonely, selfish and maladjusted. … Falbo and Polit later completed a second quantitative review of more than 200 personality studies. By and large, they found that the personalities of only children were indistinguishable from their peers with siblings.

In fact, only kids might actually be better off in key ways. Falbo’s research indicates that “only children tend to do better in school and get more education — college, medical or law degrees — than other kids.” And other researchers “have crunched the numbers from years of standardized tests like the National Merit Scholarship exam to measure verbal and mathematical abilities. In each category, only children performed better than children from larger families,” Sandler reports.

So why do the negative stereotypes about only kids persist? McKibben, Sandler, and others pin the blame on a man born more than 150 years ago, psychologist Granville Stanley Hall. His 1896 study “Of Peculiar and Exceptional Children” determined that a high proportion of unusual kids were only kids, leading him to declare, “Being an only child is a disease in itself.” But it was not a “study” in any sense that we would accept today. As McKibben told me, “Hall asked teachers around the country to submit examples of peculiar children — that could be children who were ugly, or pretty, or could lift a lot of weight, or were fussy eaters — and it was even fine if they were characters in novels. The study determined that only children, and children of immigrants, were odd. Because there were no other studies for a very long time, it became deeply received wisdom.”

And there you have it. The sole sum of evidence that only kids are weird.

I asked McKibben if his daughter, who’ll soon be heading off to college, did indeed turn out all right. “It’s a bad thing to use your own progeny as proof of your idea,” he said, “but it would be hard to imagine a nicer, better, smarter, kinder, more interesting, more interested person than she. As far as I can tell, there are no problems at all with her singletonness.”

McKibben stresses that he doesn’t want to criticize other parents or tell them how many kids to have, and he certainly doesn’t want governments mandating family size. He simply wants to make the point that our long-held suspicions of only children are baseless. The only kids are alright.

And, as McKibben wrote in his intro, Maybe One was intended to “open a debate, to remove ‘population’ from the category of abstraction and make it the very real consideration of how many children you or I may decide to bear. No single decision any of us will make will mean as much to our own lives or to the life of the planet.”

Recent research bears that out. According to a 2009 study published in Global Environmental Change [PDF], an American can prevent 20 times more carbon pollution by having one fewer kid than by adopting a number of eco-friendly habits (like driving less, switching to efficient windows and lightbulbs, etc.) for an entire lifetime. In the long term, the study authors determined, each child increases a parent’s carbon legacy by about 570 percent, because kids are likely to have kids of their own and so forth.

Discussions about family size and environmental impact can get ugly and inane. As someone who’s been writing on the subject for a while, I know this all too well. So does New York Times environment blogger Andrew Revkin. In 2009, during an online video forum, Revkin said, “Probably the single most concrete and substantive thing an American, a young American, could do to lower their carbon footprint is not turning off the lights or driving a Prius — it’s having fewer kids.” He floated a “thought experiment” about whether one-child families should get carbon credits. Right-wingers got wind and went bonkers. Rush Limbaugh ranted, “Mr. Revkin, why don’t you just go kill yourself, and help the planet by dying.”

Revkin, like most environmentally concerned people, has neither suicidal nor homicidal instincts. He’s a parent himself. He merely makes the point that with world population headed for 7 billion this year, resources dwindling, and climate change raging, it’s past time to start talking about the connections between our reproductive choices and the kind of world we’ll be leaving to the next generation.

Editor’s note: McKibben serves on Grist’s board of directors.